Enhancing Convective Heat Transfer in Porous Microchannels Using Magnetic Nanofluids and External Magnetic Fields

The effective dissipation of thermal energy remains a persistent and critical issue in modern engineering systems, particularly those characterized by miniaturization or geometric complexity. Motivated by limitations inherent in conventional cooling paradigms, this study explores the increase of convective heat transfer in porous microchannels, enhanced by applying magnetic fields. A detailed two-dimensional computational fluid dynamics (CFD) simulation was undertaken, Analyzing the flow behavior of a Fe₃O₄-water nanofluid in a microchannel featuring a porous structure. The study systematically evaluated the thermal and hydrodynamic performance under varying magnetic field intensities (spanning 800 to 1400 Gauss) and utilizing distinct magnet array configurations (two magnets versus four magnets). Findings reveal that the imposition of magnetic fields yields a statistically significant enhancement in heat transfer efficacy, particularly within intermediate flow regimes. At a Reynolds number approximating 600, the four-magnet configuration, subjected to a 1400 Gauss field, manifested a maximum Nusselt number increment of 58.4%, indicative of substantial improvement in thermal dissipation capabilities. However, as the flow transitions towards an inertia-dominated regime at elevated Reynolds numbers (≈1800), the effect of the magnetic field diminishes correspondingly, with the (PEC) asymptotically approaching unity. Furthermore, pressure drop penalties engendered by magnetohydrodynamic forces are observed to be most pronounced at lower flow rates, while a gradual decline as the Reynolds number is increased. These observations provide a valuable empirical and theoretical foundation for the design of high-performance microchannel thermal management systems predicated on the synergistic exploitation of magnetohydrodynamic principles and the thermophysical properties of ferrofluids.